中文说明：FOCUS是连续和瞬时波超声模拟器设计成模拟在各种媒体超声波。FOCUS充分利用了两种主要的模拟方法：快速近场法（FNM）和角谱法（ASA）。科FNM用于计算接近传感器表面压场，而角谱方法来快速计算出远场的压力。
English Description：
FOCUS is a continuous and transient wave ultrasound simulator designed to simulate ultrasound waves in a variety of media. FOCUS takes advantage of two primary simulation methods: the Fast Nearfield Method (FNM) and the Angular Spectrum Approach (ASA). ke FNM is used for calculating pressure fields near the transducer face, while the Angular Spectrum Approach is used to quickly calculate the farfield pressure.